Ferroresonant voltage regulator with saturable and unsaturable transformers

ABSTRACT

A ferroresonant voltage regulator has one of the secondaries of an unsaturable transformer connected in series-aiding with one of the windings of a saturable transformer or autotransformer and is included directly in a ferroresonant circuit. A capacitor is connected across the series connection of the secondary winding to form the ferroresonant circuit.

United States Patent [72] Inventors Roblen Khorenovich Balian, ulitsaDrezdenskaya, 20, kv. 5, Leningrad; Igor Efimovich Brusiiovsky, ulitsaKravehenko, l2, kv. 221, Moscow; Mark Isaakovich Roshal, ulitsaParkhornenko, 47, kv. 8,

Leningrad, all of U.S.S.R, App]. No. 2,987 Filfid J81]. 15, 1970Patented Oct. 5, 1971 FERRORESONANT VOLTAGE REGULATOR WITH SATURABLE ANDUNSATURABLE TRANSFORMERS 5 Claims, 5 Drawing Figs.

US. Cl 323/45, 323/60 Int. Cl G05f 3/06 Field of Search 323/45, 57, 60,61

Primary ExaminerWilliam H. Beha, Jr. Assistant ExaminerA. D. PellinenAttorney-Waters, Roditi, Schwartz & Nissen ABSTRACT: A ferroresonantvoltage regulator has one of the secondaries of an unsaturabletransformer connected in series-aiding with one of the windings of asaturable transformer or autotransformer and is included directly in aferroresonant circuit. A capacitor is connected across the seriesconnection of the secondary winding to form the ferroresonant circuit.

FERRORFSONANT VOLTAGE REGULATOR WITH SATURABLE AND UNSATURABLETRANSFORMERS The present invention relates to AC voltage regulation, and

more specifically to ferroresonant voltage regulators.

The invention may be used in supply sources for various devices, notablytelevision receivers, in cases where the main supply is somewhatunstable.

There exist ferroresonant voltage regulators comprising a saturabletransformer (or autotransformer); an unsaturable transformer (or anunsaturable reactor with a series winding) whose primary is connected inseries with the primary of the saturable transfonner (autotransformer),usually having an airgap core; and a capacitor placed across one of thewindings (or a part thereof) of the saturable transformer(autotransformer) and forming, along with it, a parallel ferroresonantcircuit tuned to the fundamental frequency of the output voltage.

In all existing ferroresonant voltage regulators the secondary of theunsaturable transformer is connected in series with the load and is notincluded in the ferroresonant circuit directly. n the other hand, thesecondary of the unsaturable transformer is connected so as to produce abucking effect on the voltage across the secondary of the saturabletransformer (autotransformer), thereby compensating the partialinstability of the output voltage due to the finite value of the slopeof the magnetization curve of the saturable transformer(autotransformer), and this is the sole function of the compensatingwinding.

ln existing voltage regulators the voltage across the load is maintainedstabilized against variations in the supply voltage mainly by varyingthe magnitude of the voltage across the main winding of the unsaturabletransformer. The magnitude of this voltage and its variations due toregulation must be sufficiently great to make up for total variations inthe supply voltage.

A major disadvantage of existing ferroresonant voltage regulators isthat it takes a large amount of steel and conductor material to makethem. Another disadvantage is that the capacitor of the mainferroresonant circuit is of high value. Still another disadvantage is aconsiderable total weight.

An object of the present invention is to eliminate the abovementioneddisadvantages.

A specific object of the invention is to provide a ferroresonant voltageregulator which, for the same performance, takes substantially lesssteel and conductor material to make it, uses a capacitor of smallervalue, and has a smaller total weight along with an improved powerfactor and better efficiency.

The present invention consists of connecting one of the secondaries ofan unsaturable transformer in a ferroresonant voltage regulator inseries-aiding with one of the windings of a saturable transfonner(autotransformer) so as to obtain a eumulative interaction of thesewindings and forms a portion of a ferroresonant circuit tuned to thefundamental frequency of the voltage. As a result, the output terminalsintended for connecting a load are coupled directly to the secondary ofthe saturable transformer (autotransformer). The output terminals canalso be connected to the ends of a circuit made up of theseries-connected secondaries of the unsaturable transformer and thesaturable transformer (autotransformer). In both cases the capacitivecurrent of the resonant circuit flows directly through the saidsecondary of the unsaturable transfonner. This winding may be connectedin series with either the secondary or the primary of the saturabletransformer (autotransformer).

For the specified stability of output (load) voltage and temperaturerise, the regulator disclosed herein takes less steel and conductormaterial to make it, uses a smaller capacitor, and has a smaller weightalong with an improved power factor and better efficiency.

The invention will be best understood from the following description ofa preferred embodiment when read in connection with the accompanyingdrawings wherein:

FIG. 1 shows a circuit schematic of the voltage regulator disclosedherein, with the secondary of an unsaturable transformer connected inseries with the secondary of a saturable autotransformer; i

FIG. 2 shows the voltage vector diagram of the voltage regulatordisclosed herein;

FIG. 3 shows a circuit schematic of the voltage regulator disclosedherein, with the secondary of an unsaturable transformer connected inseries with the secondary of a saturable transformer;

FIG. 4 shows a circuit schematic of the voltage regulator disclosedherein, with the secondary of an unsaturable transformer connected inseries with the primary of a saturable transformer; and

FIG. 5 shows a circuit schematic of a voltage regulator according to theinvention, with the secondary of an unsaturable transformer connected inseries with the secondary of a saturable autotransformer, and with thecapacitor of the ferroresonant circuit used to reduce thenonlineardistortion of the output voltage.

Referring to FIG. 1, there is a voltage regulator comprising: asaturable autotransformer l with a core 2, a primary 3, and a secondary4; an unsaturable transformer 5 with a core 6 having an airgap, aprimary 7, and a secondary 8; a capacitor 9 which along with theautotransformer l and the unsaturable transformer 5 makes up a parallelferroresonant circuit tuned to the fundamental frequency of the voltage.The main voltage is impressed on the winding 3 of the autotransformer 1through the winding 7 of the transformer 5, connected in series with it.The secondary 4 of the autotransformer l and the secondary 8 of thetransformer 5 are connected series-aiding and are coupled to theterminals of the capacitor 9.

The output terminals 10' and 11 intended for connecting a load can becoupled to the secondary of the saturable trans former(autotransformer). In some types of regulators the output terminals 10and I] intended for connecting a load are coupled to the ends of theseries-connected windings 8 of the unsaturable transfonner 5 and thewindings 4 of the saturable transformer (autotransformer).

In the voltage regulator disclosed herein, variations in the supplyvoltage are compensated mainly by varying the phase displacement betweenthe voltages across the winding 7 of the unsaturable transformer 5 andthe winding 3 of the saturable autotransformer 1, while their magnitudesare changed but little, which is favored by the fact that the secondary8 of the transformer 5 is energized with a capacitive current at thefundamental frequency. This is illustrated by the voltage vector diagramof FIG. 2 where:

U is the saturable autotransformer primary voltage vector;

U is the minimum supply voltage vector;

U is the nominal supply voltage vector;

U is the maximum supply voltage vector;

U is the unsaturable transformer primary voltage vector;

a is the minimum phase displacement between U and UCMII;

a is the nominal phase displacement between U and Cnnm;

a is the maximum phase displacement between U and Cmtn- Since in thevoltage regulator disclosed herein regulation of the output voltage doesnot involve large changes in the magnitude of the voltage across thewinding 7 of the unsaturable transformer 5, it is possible to reduceboth its inductance and the value of the saturation current of thesaturable autotransformer 1.

As a consequence, it is possible to reduce the size and weight of theautotransformer l and transformer 5, and also the energy taken up by thecapacitor 9 compensating the saturation current, without jeopardizingthe stabilization effect, the power factor, and the efficiency. This isalso facilitated by the fact that within the main zone ofregulation-from the nominal to the minimum voltage-the voltage acrossthe capacitor 9 is greater than in conventional types, because withinthis zone and with the circuit connections as proposed the sum' of thevoltages across the windings 4 and 8 is greater than each voltage takenseparately. As a result, there is an increase in the reactive powerdelivered by the capacitor. On the other hand, the maximum capacitorvoltage occurring when the supply voltage increases and governing thechoice of the capacitor is the same as in conventional regulations,because in the case of an increase in the supply voltage the voltagesacross the windings 4 and 8 are displaced in phase (FIG. 2) so thattheir sum is practically equal in magnitude to the voltage across thewinding 4.

In the regulator disclosed herein, the saturable autotransformer may bereplaced by a saturable transformer (FIG. 3).

In some cases the secondary 8 of the unsaturable transformer 5 may beconnected in series with the primary 3 of the saturable transformer(autotransformer) 1 (FIG. 4).

In a practical voltage regulator, it is convenient to provide taps onthe windings 3 and 4 of the saturable transformer (autotransfonner) land on the windings 7 and 8 of the unsaturable transformer 5 for optimaltuning, as is usually done on ferroresonant regulators.

Furthermore, it is advisable to use the capacitor of the ferroresonantcircuit additionally for control of nonlinear distortion in the outputvoltage by connecting it in series with a suitable tapped reactor, as isusually done in existing types of ferroresonant regulators.

FIG. 5 shows a circuit schematic of a ferroresonant voltage stabilizermade in accordance with the invention, in which the capacitor 9 of theferroresonant circuit is used along with a reactor 12 for control ofnonlinear distortion in the output voltage, the tap 13 of this reactorbeing used, as is usually done, for connection of the load for a furtherreduction in the nonlinear distortion of the output voltage.

This regulator is intended for use in television receivers with a powerrating of up to 220 volt-amperes. The nominal supply voltage to beregulated may be 220 volts and 127 volts (a changeover from one to theother is not shown in FIG. 5, because it is of minor consequence).Voltage regulators of this type can maintain an output to within :l or 2percent for a variation of 0 percent of the supply voltage, which ismore than enough for television receivers. With a small decrease in thestability of the output, still lying within the limits specified fortelevision receivers, the range of variations in the supply voltage thancan be regulated may be extended to 30 percent. .As measured at thenominal supply voltage, the efficiency is not less than 85 percent, thepower factor (in terms of regulator input values) is not less than 0.87,the nonlinear distortion factor is about 7 percent, and the temperaturerise of the transformer and reactor windings is not over 55 C. when theregulator is built into a plastic case, and a little lower with a metalcase.

With the characteristics as given above, the weight of the cores (madeof silicon-iron strip or punched l'aminations) is 2 kg., that of thecopper in the windings is 1 kg., the capacitance of the capacitor is 10to 12 microfarads with a rated voltage of 250 volts RMS, and the totalweight of the voltage regulator complete with all structural elementsand built into a case is not over 4.5 kg. When use is made of aluminumconductors, the weight of the active material and of the regulator as awhole is further reduced.

In the voltage regulator having the characteristics quoted above use ismade of ordinary enamel-insulated wire of normal thermal stability (thatis, capable of operation at the class A temperatures). With wire of agreater thermal stability, a further improvement in the performance maybe obtained. ln contrast, existing ferroresonant voltage regulators havea much greater weight, a greater capacitor, and take more iron andcopper (1.5 to 3 times as much) to give the same electricalcharacteristics. The voltage regulator disclosed herein has a first costreduced accordingly.

Thus, a ferroresonant voltage regulator built in accordance with thepresent invention offers advantages, both technical and economical, overexisting types.

What is claimed is: l. A ferroresonant voltage regulator comprising: asaturable autotransformer and an unsaturable transfonner having at leastone secondary, the primary of said autotransformer connected in serieswith the primary of said unsaturable transformer and a capacitorconnected across a series connection of one secondary of the unsaturabletransformer and one of the windings of the saturable autotransformer, toform a parallel ferroresonant circuit tuned to the fundamental frequencyof the voltage.

2. A ferroresonant voltage regulator as claimed in claim 1, includingoutput terminals for connection to a load, said output terminals beingcoupled directly to the secondary of the saturable autotransformer.

3. A ferroresonant voltage regulator as claimed in claim 1, wherein saidwinding of said saturable autotransformer is the secondary winding, saidregulator including output terminals for connection to a load, saidoutput terminals being coupled to the ends of a circuit formed of thesecondaries of the unsaturable transformer and of the saturableautotransformer connected in series.

4. A ferroresonant voltage regulator, as claimed in claim 1, whereinsaid winding of said saturable autotransformer is the secondary winding,the secondary winding of the unsaturable transformer being connected inseries-aiding with the secondary of the saturable autotransformer.

5. A ferroresonant voltage regulator, as claimed in claim 1, wherein thewinding of said saturable autotransformer is the primary winding, thesecondary of the unsaturable transformer being connected inseries-aiding with the primary of the saturable autotransformer.

1. A ferroresonant voltage regulator comprising: a saturableautotransformer and an unsaturable transformer having at least onesecondary, the primary of said autotransformer connected in series withthe primary of said unsaturable transformer and a capacitor connectedacross a series connection of one secondary of the unsaturabletransformer and one of the windings of the saturable autotransformer, toform a parallel ferroresonant circuit tuned to the fundamental frequencyof the voltage.
 2. A ferroresonant voltage regulator as claimed in claim1, including output terminals for connection to a load, said outputterminals being coupled directly to the secondary of the saturableautotransformer.
 3. A ferroresonant voltage regulator as claimed inclaim 1, wherein said winding of said saturable autotransformer is thesecondary winding, said regulator including output terminals forconnection to a load, said output terminals being coupled to the ends ofa circuit formed of the secondaries of the unsaturable transformer andof the saturable autotransformer connected in series.
 4. A ferroresonantvoltage regulator, as claimed in claim 1, wherein said winding of saidsaturable autotransformer is the secondary winding, the secondarywinding of the unsaturable transformer being connected in series-aidingwith the secondary of the saturable autotransformer.
 5. A ferroresonantvoltage regulator, as claimed in claim 1, wherein the winding of saidsaturable autotransformer is the primary winding, the secondary of theunsaturable transformer being connected in series-aiding with theprimary of the saturable autotransformer.